var treeData = [
  { id: 1, title: '一级菜单', pid: 0 },
  { id: 2, title: '二级单01', pid: 1 },
  { id: 3, title: '二级单02', pid: 1 },
  { id: 4, title: '二级单03', pid: 1 },
  { id: 5, title: '一级菜单02', pid: 0 },
  { id: 6, title: '二菜单01', pid: 5 },
  { id: 7, title: '三菜单01', pid: 6 },
  { id: 8, title: '三菜单02', pid: 6 },
  { id: 9, title: '四级菜单01', pid: 8 },
  { id: 10, title: '四级菜单02', pid: 8 },
  { id: 11, title: '二级菜单01', pid: 5 },
  { id: 12, title: '二级菜单02', pid: 5 },
  { id: 20, title: '一级菜单03', pid: 0 },
  { id: 21, title: '一级菜单03', pid: 20 },
];
